System-wide values of header arguments can be specified by adapting the
org-babel-default-header-args variable:
:session => "none" :results => "replace" :exports => "code" :cache => "no" :noweb => "no"
This example sets :noweb header arguments to yes, which makes
Org expand :noweb references by default.
(setq org-babel-default-header-args
(cons '(:noweb . "yes")
(assq-delete-all :noweb org-babel-default-header-args)))